1. Field of the Invention
The present invention relates generally to a process for removing impurities from feeds or streams comprising organic liquids. More particularly, it concerns the removal of aldehydes, esters, and related oxygenate impurities from feeds or streams comprising organic chemicals such as hydrocarbons and epoxides.
2. Description of Related Art
During the commercial manufacture of alkylene oxides, oxygenate impurities such as aldehydes and esters are typically produced. Such oxygenate impurities can be very difficult to separate from the alkylene oxide product, due to the small differences in boiling points and other physical properties between the product and the impurities. For example, in the manufacture of propylene oxide, a great deal of effort typically must be devoted to separating the product from the close boiling formaldehyde, acetaldehyde, methyl formate, and other impurities.
Numerous processes have been developed for separating alkylene oxide product from accompanying oxygenate impurities. For example, U.S. Pat. No. 4,691,034 discloses a process for removing methyl formate from propylene oxide via contacting the product mixture with an aqueous calcium hydroxide slurry to which a solubilizer has been added. Similarly, U.S. Pat. No. 4,691,035 discloses a process for removing methyl formate from propylene oxide via contacting the product mixture with a base such as sodium hydroxide in water and glycerol. A method for removal of methyl formate from ethylene oxide, propylene oxide, and butylene oxide by contacting the alkylene product mixture with a basic ion exchange resin is disclosed in U.S. Pat. No. 5,107,002. While these processes address the removal of methyl formate impurities which may be present in alkylene oxide product mixtures, they do not address the removal of aldehyde impurities which may also be present in alkylene oxide product mixtures.
U.S. Pat. No. 3,816,478 discloses a method for removal of aldehyde impurities from organic liquids by passing the organic liquids over a bed consisting essentially of solid particles of sodium bisulfite. However, this method does not address the removal of ester impurities, such as methyl formate, which may also be present in alkylene oxide streams.